The 'fuel' used to generate power from the sun or the wind is, of course, emissions free. But we realize that it is necessary to look at more than just the fuel input in evaluating the total impacts of various technologies. Life-cycle analysis (LCA) goes beyond the operational comparison and also looks at the impacts of creating the equipment to harness those energies as well as the effects of decomissioning them at their end of life.
Research by the National Renewable Energy Laboratory (NREL) has looked at a wide range of studies carried out to asess the greenhouse gas effects related to different forms of energy. THe NREL meta-study sought to equalize and balance the different studies carried out by different researchers in such a fashion that they could be compared with each other.
The conclusions show that "greenhouse-gas emissions from wind power and solar photovoltaics are about 5% of those from coal and that nuclear energy emissions are on par with those from renewable energy."
Renewables such as solar and wind produce far fewer greenhouse-gas emissions than coal, oil or natural gas while in operation. But the meta-analysis looked even deeper, at emissions estimates starting with the manufacture of solar panels, wind turbines, coal plants or natural-gas lines, all the way to the emissions estimates for decommissioning the sites.
While it may seem intuitively obvious, the ability to cross-compare between different studies has not been there previously, and this will allow for better comparison between different techologies, as well as giving a more even picture of the benefits of renewable energy.
via: NA Windpower